1. Field of the Invention
The present invention relates to a rotor balancing structure, a sheet material processing device, and an image forming device.
2. Description of the Related Art
There has been provided an image exposure device in which a light-sensitive printing plate (referred to as a xe2x80x9cprinting platexe2x80x9d hereinafter) having a light-sensitive layer formed on a sheet-type support such as thin aluminum is wound around a rotating drum, a light beam corresponding to image data is irradiated onto the printing plate while the rotating drum is being rotated at high speed (for example, 600 rpm or more), and the printing plate is thereby scanned and exposed.
In a case in which the printing plate has been wound around the rotating drum, sometimes, an unbalanced state in which the center of gravity of the rotating drum deviates from the center of rotation may occur. When the rotating drum is made to rotate at high speed in an unbalanced state, vibration occurring at the rotating drum may damage an image to be formed on the printing plate that has been wound around the rotating drum, and may furthermore produce noise or damage the interior of the device.
In order to prevent such an unbalanced state from occurring, there is provided a method in which, when the printing plate is wound around the rotating drum and attached thereto, balancing weights are mounted to the rotating drum. The balancing weight is mounted in such a way that the amount of unbalance, which is a displacement between the center of rotation of the rotating drum and the center of gravity thereof, is measured or calculated on the basis of a weight of the printing plate and a position at which the printing plate is mounted to the rotating drum. The weight of the balancing weight and the position at which the printing plate is mounted to the drum are calculated so as to correct the unbalanced state. On the basis of the calculation, a balancing weight may be mounted to the rotating drum, or the balancing weight which has already been mounted to the drum may be moved.
The size of the printing plate is determined so as to correspond to a size of prints. For this reason, a plurality of cassettes in which printing plates of different sizes are respectively accommodated are mounted at the image exposure device, a printing plate of a specified size is taken out from a corresponding cassette and is then mounted at the rotating drum.
If the size of the printing plate differs, the weight thereof changes. Further, the amount of unbalance when the printing plate is wound around the rotating drum changes in accordance with the size of the printing plate. At this time, when a size of the printing plate is input manually by an operator in order to balance the rotating drum, if the operator inputs a wrong printing plate size, the rotating drum is made to rotate in an unbalanced state, thus causing damage to the image exposure device or the like.
In order to prevent such damage to the image exposure device or the like due to the inputting of a wrong printing plate size, it might be thought that a sensor for detecting whether the rotating drum is rotating in an unbalanced state could be provided at the device, such that the rotation of the rotating drum is stopped immediately when the rotating drum has been judged by the sensor to be in an unbalanced state. However, were such a sensor to be provided, the interior of the device would become complicated.
On the other hand, there is also provided a method in which the size of the printing plate that has been wound around the rotating drum is detected by a sensor. However, in this case also, in order to provide the sensor for detecting the size of the printing plate, the interior of the device becomes complicated, and in addition to a sequence for adjusting the balancing weight, another sequence for detecting the size of the printing plate must be provided before the rotating drum rotates, thus becoming an obstacle to rapid exposure processing.
In view of the aforementioned facts, an object of the present invention is to provide a rotor balancing structure that can rotate and drive the rotor with an appropriate balance without using a sequence for correcting an unbalanced state of the rotor.
Further, it is another object of the present invention to provide a sheet material processing device and an image forming device that have been improved in the same manner as the rotor balancing structure.
In order to solve the aforementioned problems, there is provided a rotor balancing structure for rotating an object, the structure comprising: (a) a rotor to which an object can be removably fixed; (b) a support rotatably supporting the rotor and elastically supporting the rotor so that the rotor may be displaced in a radial direction thereof at the time that the rotor to which the object has been fixed is rotated; and (c) a balancer that can rotate together with the rotor and alter a position of the center of gravity of the balancer, such that a dynamic balance of the overall rotor including the object at the time that the rotor to which the object has been fixed is rotated can be obtained.
A sheet material processing device according to the present invention comprises: (a) a rotatable drum having an outer circumference around which a sheet material can be wound and fixed; (b) a driving device which rotates the drum when operated; (c) a support that can support a rotation of the drum and elastically support the drum so that the drum may be displaced in a radial direction thereof at the time that the drum around which the sheet material has been wound and fixed is rotated; (d) a balancer that can rotate together with the drum and alter a position of the center of gravity of the balancer, such that a dynamic balance of the overall drum including the sheet material at the time that the drum to which the sheet material has been wound and fixed is rotated can be obtained; and (e) a processing element for applying a predetermined processing to the sheet material on the outer circumference of the drum.
An image forming device according to the present invention comprises: (a) a rotatable drum having an outer circumference around which a printing plate can be wound; (b) a driving device which rotates the drum when operated; (c) a support that can support a rotation of the drum and elastically support the drum so that the drum may be displaced in a radial direction thereof at the time that the drum around which the printing plate has been wound is rotated; (d) a balancer which can rotate together with the drum and alter a position of the center of gravity of the balancer, such that a dynamic balance of the overall drum including the sheet material at the time that the drum to which the sheet material has been wound and fixed is rotated can be obtained; (e) a recording device for recording an image onto the printing plate at the outer circumference of the drum; and (f) wherein the driving device and/or the recording device, rather than rotating with the drum, are structured to be able to move in accordance with a displacement of the drum.